check out: The treehouse is a "collective housing" designed to accomodate many birds and one person. On one side, the treehouse has entrances to 78 nest spaces for birds. The other side has an entrance for one person, who can look into the birds' nests through "peep holes" from inside the treehouse.
website: http://momofukucenter.jp/
address in Japanese:
安藤百福記念 自然体験活動指導者養成センター 〒384-0071 長野県小諸市大久保1100番